Red Bull have come to Barcelona making no bones about their need to fight for victory in order to kick-start their world championship title aspirations. But, on this showing, Mercedes have opened the gap over the opposition despite this being the venue at which everyone traditionally brings upgrades to make their cars go faster.
These are usually aerodynamic, based on what teams have gleaned from their own ongoing research programmes and/or what they have learned from rivals. However, this year it also embraces software upgrades designed to enhance the performance of the complex 1.6-litre eco-hybrid powerplants.
At the end of the sessions for Sunday's Spanish Grand Prix, Lewis Hamilton was a 10th of a second quicker than Fernando Alonso's Ferrari and half a second up on Daniel Ricciardo's Red Bull. The Englishman was respectively 1.597sec and 0.985sec faster, on the track that incorporates a little bit of everything and is therefore regarded as one which highlights the likely form over the remainder of the season.
To be fair, Red Bull endured another day from hell with Sebastian Vettel's car. It had been fitted with a different chassis since the Chinese Grand Prix three weeks ago, in what the four-time champion described as a "sanity test" to make sure that his lack of speed in previous races was not down to that part of his equipment.
But the chassis with which he had problems in pre-season testing continued to undermine his hopes. He lost an hour of the 90 minutes available in the morning session through electrical problems, and was unable to run at all in the afternoon because of the resultant damage.
A brief statement from Red Bull simply said: "The team will use the time to fix it to be ready for FP3 tomorrow."
Given that Ricciardo has been at least as quick as Vettel in the previous four races, however, it's unlikely that the German would have got much closer to the Mercedes.
Hamilton dominated both sessions with marked ease, the first by 0.868sec from surprise runner-up Jenson Button in an improved McLaren, the second by 0.449sec from Rosberg.
"It's been a great day today and I'm happy to be back in the car after what feels like quite a long break," Hamilton said, clearly revelling in his unaccustomed role as the unchallenged performance yardstick.
"I can really feel the positive step forward that we've made with the car, so a big thank you to everyone back at our factories for all of their hard work since China.
"Our two practice sessions today went very smoothly, in fact I've not had such a good Friday for a very long time. Barcelona is a difficult circuit in terms of the tyres, so our running was all about trying to see how long the tyres would last, and we were able to make some positive changes with that this afternoon.
"It's very difficult to overtake here, so we will do everything we can to qualify as high a position as possible tomorrow, but really it is all about the race and looking after those tyres is the most important thing."
Worryingly for the Silver Arrows' rivals, the race speed of the W05 and its control of tyre degradation looked very impressive. Hamilton, in particular, was at least a second faster than either Red Bull and Ferrari.